Two new cyclolanostanol triterpene glycosides, cimifoetiside VI (1) and cimifoetiside VII (2), and one known compound were isolated from the aerial parts of Cimicifuga foetida L. On the basis of spectral and chemical evidences, the structures of 1 and 2 were elucidated to be (23R,24S)-24-O-acetylisodahurinol-3-O-beta-d-galactopyranoside and (23R,24R)-24-O-acetylshengmanol-3-O-beta-d-glucopyranosyl-(1'' --> 2')-beta-d-xylopyranoside. The known compound was identified as (23R,24R)-24-O-acetylshengmanol-3-O-beta-d-galactopyranoside (3).
Triterpenoids are a large and medicinally important group
of natural
products with a wide range of biological and pharmacological effects.
Among them, malabaricane-type triterpenoids are a rare group of terpenoids
with a 6,6,5-tricyclic ring system, and a few malabaricane triterpene
synthases have been characterized to date. Here, an arabidiol synthase
AmAS for the formation of the malabaricane-type 6,6,5-tricyclic triterpenoid
skeleton in astramalabaricosides biosynthesis was characterized from Astragalus membranaceus. Multiple sequence alignment, site-directed
mutagenesis, and molecular docking of AmAS reveal that residues Q256
and Y258 are essential for AmAS activity, and the triad motif IIH725-727
was the critical residue necessary for its product specificity. Mutation
of IIH725-727 with VFN led to the formation of seven tricyclic, tetracyclic,
and pentacyclic triterpenoids (1–7). Glycosylation of malabaricane-type triterpenoids in the biosynthesis
of astramalabaricosides was also explored. Three triterpenoids (1, 5, and 6) displayed potent inhibitory
effects against influenza A virus in vitro. These findings provide
insights into malabaricane-type triterpenoids biosynthesis in A. membranaceus and access to diverse bioactive triterpenoids
for drug discovery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.